1. Field of the Invention
The invention relates to devices for the magnified viewing of an object, comprising an objective, a left eyepiece and a right eyepiece.
2. Description of the Background Art
Such optically magnifying devices, for example conventional binoculars or professional microscopes, have one eyepiece each for each eye of a user in order to permit viewing of an object over a prolonged period without premature fatigue. In contrast to a monocular telescopic sight, for example, a target object a long distance away can, if required, also be viewed for hours in an ergonomic manner. Such an optically magnifying device can also be provided with a display by means of which an image can be made available to the user, optionally also during the magnified viewing of the object. This image may be, for example, a thermal image of the object, a night vision image or an image having a represented measured value. Accordingly, prolonged viewing of the display without premature fatigue is also possible only via two eyepieces.
The two eyepieces of such devices must be formed in a manner known per se so as to be movable relative to one another in order to be able to adapt the spacing of the eyepieces to the individual eye spacing of the viewer. A left-eye and right-eye beam of optical rays can be projected into the left and right eye of the user via the left eyepiece and right eyepiece, respectively. These beams must correspond to one another in a manner known per se within narrow optical tolerances in order to avoid causing the user a headache on prolonged viewing. If the entry area for object rays emanating from the object is dimensioned to be appropriately large and transmission losses caused by the device are kept small, the projected visual field rays have an intensity which permits prolonged viewing of a distant object even under less optimal light conditions.
Hand-held devices in the form of conventional binoculars which are intended for viewing a distant object have a left-eye and a right-eye direct vision system having in each case an objective, an image inversion system and an eyepiece. As a rule, both direct vision systems are designed to be optically identical and are connected to one another via a folding mechanism. This permits in a simple manner the required mobility of the eyepieces with simultaneous compliance with the narrow tolerances with respect to the parallelism of the optical axes of the two direct vision systems and the optical imaging of the two separate beams. In this way, it is possible to realise light and robust devices for convenient viewing of distant objects, which devices can be held by the user himself in his hand and can be carried to the place of use. When provided with high-quality direct vision optical systems, they can also be used under less optimal light conditions, for example in twilight.
Since, when viewing a distant object using binoculars, information about the distance thereof relative to the user is often also of interest different measuring sensors, for example distance meters and/or magnetic compasses are integrated in so-called measuring binoculars. DE 37 04 848 A1 discloses such measuring binoculars in which measured values shown on a display are input via a physical beam splitter surface into the left-eye direct vision system and made available to the user during viewing of the distant object. At the physical beam splitter surface, rays collected by the objective are inevitably lost during such input, at least from the wavelength range of the input rays. This is disadvantageous particularly in the case of polychromatic displays. In addition, a part of the rays emanating from the display is also inevitably lost at the same physical beam splitter surface. Since the major part of the energy demand of such measuring binoculars is now due to the display, input losses of display rays additionally aggravate the energy supply problem present as a rule in the case of such portable devices.
U.S. Pat. No. 5,579,165 discloses computerised binoculars having two separate direct vision systems which have a digitally actuatable screen display with a multiplicity of pixels. By means of these, not only measured values but also recorded or computer-generated images can be projected into one of the two beam paths of the binoculars and optionally superimposed on a direct vision image. If a recorded and displayed image of the same object is to be superimposed on a direct vision image of an object, the precision of such a superimposition must meet high requirements so that the user does not see troublesome multiple images. For prolonged viewing, it would be possible in principle to provide two screen displays. However, this would have adverse effects on the energy consumption and the production costs of the device.
US 2002/0034004 A1 discloses binoculars having two separate direct vision systems which have a common display for the two separate direct vision systems. Via optical switches and partly transparent mirrors, it should be possible in this way to superimpose a digital image of the display alternately on the two direct vision images. Significant parts of the rays emanating from an object and from the common display would be lost thereby at the two disclosed physical beam splitter surfaces which are provided in the two separate beam paths of the direct vision systems, in particular in the case of a polychromatic display.
U.S. Pat. No. 6,204,961 discloses a day/night vision sighting system which has a direct vision system, a distance metre and an indirect vision system with an infrared image sensor and a display also for reproducing images recorded by the infrared image sensor. During use at night, images recorded by the infrared image sensor are made available to the user via the display, a partly transparent mirror and a single eyepiece. Such day/night vision sighting systems are now in the form of monocular laser distance metres or monocular telescopic sights which are not very suitable for prolonged observation.